"Most supernovae are visible for a short time and then -- over a matter of weeks -- fade from view," said Breanna Binder, a University of Washington. After a star explodes as a supernova, it usually leaves behind either a black hole or what's called a neutron star -- the collapsed, high-density core of the former star. Neither should be visible to Earth after a few weeks. But this supernova -- SN 2010da -- still was.
"SN 2010da is what we call a 'supernova impostor' -- something initially thought to be a supernova based on a bright emission of light, but later to be shown as a massive star that for some reason is showing this enormous flare of activity," said Binder.
Many supernova impostors appear to be massive stars in a binary system -- two stars in orbit of one another. Stellar astrophysicists think that the impostor's occasional flare-ups might be due to perturbations from its neighbor.
For SN 2010da, the story appeared to be over until September 2010 -- four months after it was confirmed as an impostor -- when Binder pointed NASA's Chandra X-ray Observatory toward NGC300 and found something unexpected.
"There was just this massive amount of X-rays coming from SN 2010da, which you should not see coming from a supernova impostor," she said.
Read the full story at The Daily Galaxy